A wide variety of medical conditions and disorders have been successfully treated using an implanted stimulator. Such a stimulator will typically stimulate internal tissue, such as a nerve, by emitting an electrical stimulation current according to programmed stimulation parameters.
One class of such implantable stimulators, also known as BION® devices (where BION® is a registered trademark of Advanced Bionics Corporation, of Valencia, Calif.), are typically characterized by a small, cylindrical housing that contains electronic circuitry that produces the desired electric stimulation current between spaced electrodes. These stimulators, also referred to as microstimulators, are implanted proximate to the target tissue so that the stimulation current produced by the electrodes stimulates the target tissue to reduce symptoms or otherwise provide therapy for a wide variety of conditions and disorders.
For example, urinary urge incontinence may be treated by stimulating the nerve fibers proximal to the pudendal nerves of the pelvic floor. Erectile or other sexual dysfunctions may be treated by providing stimulation of the cavernous nerve(s). Other disorders, e.g., neurological disorders caused by injury or stroke, may be treated by providing stimulation to other appropriate nerve(s).
In U.S. Pat. No. 5,312,439, entitled Implantable Device Having an Electrolytic Storage Electrode, an implantable device for tissue stimulation is described. U.S. Pat. No. 5,312,439 is incorporated herein by reference in its entirety.
Another microstimulator known in the art is described in U.S. Pat. No. 5,193,539, “Implantable Microstimulator,” which patent is also incorporated herein by reference in its entirety. The '539 patent describes a microstimulator in which power and information for operating the microstimulator are received through a modulated, alternating magnetic field. A coil in the microstimulator is adapted to function as the secondary winding of a transformer. This induction coil receives energy from outside the patient's body and a capacitor is used to store electrical energy which is released to the microstimulator's exposed electrodes under the control of electronic control circuitry.
In U.S. Pat. Nos. 5,193,540 and 5,405,367, which patents are incorporated herein by reference in their respective entireties, a structure and method of manufacture of an implantable microstimulator are disclosed. The microstimulator has a structure which is manufactured to be substantially encapsulated within a hermetically-sealed housing that is inert to body fluids, and of a size and shape capable of implantation in a living body with appropriate surgical tools. Within the microstimulator, an induction coil receives energy or data from outside the patient's body.
In yet another example, U.S. Pat. No. 6,185,452, which patent is likewise incorporated herein by reference in its entirety, there is disclosed a device configured for implantation beneath a patient's skin for the purpose of nerve or muscle stimulation and/or parameter monitoring and/or data communication. Such a device contains a power source for powering the internal electronic circuitry. This power supply is a battery that may be externally charged periodically, e.g., once each day. Similar battery specifications are found in U.S. Pat. No. 6,315,721, which patent is additionally incorporated herein by reference in its entirety.
Other microstimulator systems prevent and/or treat various disorders associated with prolonged inactivity, confinement or immobilization of one or more muscles. Such microstimulators are taught, e.g., in U.S. Pat. No. 6,061,596 “Method for Conditioning Pelvis Musculature Using an Implanted Microstimulator;” U.S. Pat. No. 6,051,017 “Implantable Microstimulator and Systems Employing the Same;” U.S. Pat. No. 6,175,764 “Implantable Microstimulator System for Producing Repeatable Patterns of Electrical Stimulation; U.S. Pat. No. 6,181,965 “Implantable Microstimulator System for Prevention of Disorders;” U.S. Pat. No. 6,185,455 “Methods of Reducing the Incidence of Medical Complications Using Implantable Microstimulators;” and U.S. Pat. No. 6,214,032 “System for Implanting a Microstimulator.” The applications described in these additional patents, including the power charging techniques, may also be used with the present invention. The '596, '017, '764, '965, '455, and '032 patents are incorporated herein by reference in their respective entireties.
As will be readily appreciated, a key part of patient treatment using an implanted stimulator is the proper placement of the stimulator such that the stimulation electrodes are proximate to the target tissue to be stimulated. If the stimulation electrodes are optimally placed near the target tissue, stimulation can be affected over a wide range of parameters with optimally minimal power consumption.